while the bulk of my collection is RPPC's and CDV's, i have also picked up an occasional tintype when it relates to music and is affordable (a rarity that is akin to the stars being aligned).
the image above is probably the best of the few i have, particularly because the image is not only stellar, but it retains its original frame. if you click on it you can see the hand tinted rosy cheeks (which seems to be common amongst tintype portraits) as well as the fiddler's very sporty vest.
the tintype was developed by professor hamilton k. smith in 1856.
here's a bit of history: A wet-plate collodion process produced on a thin iron plate--named the melainotype (melaino, meaning dark or black) or ferrotype (ferro, referring to iron) and popularly called the tintype--was developed in Ohio in the early 1850s. While many mid-nineteenth century photographers did not value the tintype, it held many advantages over earlier photographic processes. It was less expensive, easier and faster to produce than the silver-plated daguerreotype, and much more durable than the glass-plated ambrotype. Like the ambrotype, the tintype was simply a collodion negative image that appeared as a positive due to the black (japanned) base upon which it rested. Despite reaching the peak of its popularity during the Civil War, the tintype continued to be used well into the second quarter of the twentieth century.